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Holly Diseases: Root Rots, Leaf Spots, and Nematode Problems

Disease Reference Table

Disease	Symptoms	Pathogen/Cause	Management
Leaf Scorch	Circular to irregular tan spots in early spring/summer. Tiny black fungal fruiting structures pepper spot surface (secondary fungus). Young leaves formed in cool/damp weather damaged if exposed to hot/dry/windy weather.	Physiological/secondary fungus	No control recommended.
Nematodes	Yellowing, stunting, twig dieback. Root system small with dead areas and galls.	Criconemella, Meloidogyne, Pratylenchus, Tylenchorhynchus	Soil/root analysis required to confirm nematodes. Care for plants to reduce other stresses. If replacing shrub, fumigate and thoroughly aerate soil first.
Phytophthora Root Rot	Leaves yellow and brown spots develop; branches and eventually entire plant die.	Phytophthora cinnamomi	Remove infected plant. Do not replace with woody ornamental unless site fumigated and aerated. Protect surrounding plants with fungicide.
Spine Spot	Pinhead-sized or larger spots, often with purple halo, on leaves in late winter/early spring. Caused by ovipositing insects (formerly thought to be leaf punctures).	Insect oviposition	No control recommended.
Tar Spot	Small yellow spots on leaves turning reddish-brown with yellow halo later in summer. Autumn: flat black cushion-shaped fungal structure under leaf surface.	Rhytisma prini	No control recommended.
Thielaviopsis Root Rot	Plants stunted with branch dieback. Roots blackened.	Thielaviopsis	Inspect roots of containerized hollies before planting; do not use those with blackened roots. Apply fungicide as soil drench to protect healthy roots.

Thielaviopsis spores; Holly dieback due to Phytophthora root rot in a root cell.

Plant Disease: Holly Leaf Holes: Not Aphids, Caterpillars/Beetles; Managing Black Spot on Roses in Wet Weather: Prevention and Treatment; Aster Diseases: Symptoms, Causes, and Management Options; Common Begonia Diseases: Identification and Management Guide; Cineraria Disease Management: Fungal, Viral, and Root Rot Control; Dracaena Disease Guide: Fungal, Bacterial, and Fluoride-Related Disorders; Poinsettia Disease Guide: Comprehensive Management for Holiday Production; Ficus Disease Guide: Anthracnose, Bacterial Leaf Spot, Branch Dieback, and Physiological Disorders; Philodendron Disease Management: Bacterial, Cold Injury, and Nutritional Disorders; Spathiphyllum Disease Management: Root Rot, Nutritional Disorders, and Viral Control

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